Setting aside the American connection, the sound is alright. It reminds me of names like Paxton and Knox- surnames that are just now gaining popularity because of their trendy sounds. There's a Kenyan Olympic runner called Nixon Chepseba. If the president didn't exist, I could imagine parents considering Nixon.

That said, the president does exist, and no amount of ignoring that fact is going to make it go away. He is an absolutely horrible role model, with inspirational quotes like:
"I don't think a woman should be in any government job whatever. I mean, I really don't. The reason why I do is mainly because they are erratic. And emotional."
"With regard to the bombing, You're so goddamned concerned about civilians and I don't give a damn. I don't care."
"When the President does it that means that it is not illegal."
and, most famously, "I am not a crook."

The surname is very, very, very attached to the infamous president. Perhaps you could get away with Nixon in certain places- I really don't know whether Nixon is as well known overseas as Thatcher or as obscure as MacDonald in America. I don't know what kind of connections people would draw or if anyone would think of the president. But personally, I wouldn't want the most famous bearer of my child's name to be a crook.

i love the name. my little cousin is named Nickson Kale and a lot of people love his name because it's unique (to them , small town) honestly, if that wasn't his name, i'd pick the name for my first son.

I'm American and I like the name. I think it's strong and cute all at the same time. If you want a different spelling, I like Nixen. I think the X makes it extra masculine. Or maybe even Nixxon/Nixxen/Nixson/Nixsen/Nixzen/Nixzon. Some other spellings... Nicsen, Nicson, Niczon, Niczen Nikzon, Nikzen, Nikson, Niksen? I feel if you add a C and a K, like Nickson, Nicksen, Nickzon, or Nickzen, people will call him Nick. But if that doesn't bother you, then add the C and K.